This invention relates to the field of telecommunications, and more particularly to a protection bus and method for a telecommunications device.
Many telecommunications devices include backplanes for transmitting digital information between components of the devices. For example, a telecommunications switching system might include a backplane for transmitting digital data representing voice signals between cards associated with incoming and outgoing ports. Typically, such a system would also include one or more mechanisms to allow the system to continue functioning, at least in part, despite the failure of a card or its inability to communicate with an associated telecommunications network interface. Successful operation of the system in many instances depends heavily upon the ability of these protection mechanisms to meet the often stringent availability, flexibility, and other requirements placed on the system.
As the telecommunications industry continues to dominate the growth of the global economy, meeting availability, flexibility, and other requirements placed on switching and other systems has become increasingly important. High availability is generally considered as exceeding 99.999 percent availability, amounting to less than approximately five minutes of xe2x80x9cdown timexe2x80x9d per year, and generally requires a system to have the ability to autonomously handle certain faults, such as failure of a card or other component, without immediate human intervention. High availability has increasingly become a de facto if not explicit competitive requirement for many telecommunications manufacturers.
However, previous protection techniques are often inadequate to meet these requirements. As the density of cards within telecommunications devices continues to increase, preventing a single card failure from removing one or more other cards from service becomes increasingly important. For example, with previous techniques, the failure of one card in a switching system having twenty-four cards might result in 96 communications channels being lost if each card supports four ports, lines, trunks, or other network interfaces, while failure of a card supporting sixteen network interfaces might cause 512 channels to be lost. Since it is undesirable to allow single points of failure to propagate in high availability environments, deficiencies of prior protection techniques are particularly apparent when they are incorporated within high availability backplane environments of telecommunications devices.
According to the present invention, disadvantages and problems associated with protection strategies within a backplane environment of a telecommunications device have been substantially reduced or eliminated.
According to one embodiment of the present invention, a telecommunications device includes a protection bus, at least one protected card, and an I/O module for the protected card. The I/O module is coupled to the protected card and the protection bus and communicates data between the protected card and an associated network interface. The device also includes at least one protection card and a protection I/O module for the protection card. The protection I/O module is coupled to the protection card and the protection bus and is capable of assuming at least some responsibilities of the protected card in response to a failure of the protected card. The protection I/O module will then communicate the data between the protection card and the I/O module for the protected card using the protection bus. The I/O module for the protected card communicates the data with the network interface associated with the protected card to protect the device from the failure of the protected card.
The protection bus and related components of the present invention provide a number of important technical advantages over prior protection strategies, particularly within a high availability backplane environment of a telecommunications device. The present invention provides multiple layers of fault protection, including both detection and handling of faults associated with cards within the device, helping to prevent single points of failure from propagating within the device, reduce down time, and satisfy high availability requirements. As a result of these and other advantages, the protection bus and related components of the present invention are well suited for incorporation in a variety of switching and other modern telecommunications devices. Other important technical advantages are apparent to those skilled in the art.